Date: Mon, 30 Aug 2010 18:11:36 +0200 (CEST)
From: Gerhard Wiesinger <lists@wiesinger.com>
To: Pavel Stehule <pavel.stehule@gmail.com>
cc: Andreas Kretschmer <akretschmer@spamfence.net>,
	pgsql-performance@postgresql.org
Subject: Re: Major performance problem after upgrade from 8.3 to
 8.4
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On Mon, 30 Aug 2010, Pavel Stehule wrote:

> 2010/8/30 Gerhard Wiesinger <lists@wiesinger.com>:
>> On Mon, 30 Aug 2010, Pavel Stehule wrote:
>>
>>> Hello
>>>
>>> 2010/8/30 Andreas Kretschmer <akretschmer@spamfence.net>:
>>>>
>>>> Gerhard Wiesinger <lists@wiesinger.com> wrote:
>>>>
>>>>> I know that the data model is key/value pairs but it worked well in 8.3.
>>>>> I need this flexibility.
>>>>>
>>>>> Any ideas?
>>>>
>>>> If i understand the query correctly it's a pivot-table, right?
>>>>
>>>
>>> no - it's just EAV table on very large data :(
>>
>> Yes, it is an EAV table, but with query space comparable low (Max. 1 day out
>> of years, typically 5mins out of years).
>>
>
> it is irelevant - there are repeated seq scans - so you need a
> partitioning or classic table - maybe materialized views can help

I know the drawbacks of an EAV design but I don't want to discuss that. I 
want to discuss the major performance decrease of PostgreSQL 8.3 
(performance was ok) to PostgreSQL 8.4 (performance is NOT ok).

Any further ideas how I can track this down?
Can someone explain the difference in query plan from an optimizer point 
of view?

Thnx.

Ciao,
Gerhard

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